kdumpctl - Man Page

kdumpctl COMMAND

kdumpctl is used to check or control the kdump service. In most cases, you should use systemctl to start / stop / enable kdump service instead. However, kdumpctl provides more details for debugging and a helper to set up ssh key authentication.

start

Start the service.

stop

Stop the service.

status

Prints the current status of kdump service. It returns a non-zero value if kdump is not operational.

restart

Is equal to start; stop

reload

reload the crash kernel image and initramfs without triggering a rebuild.

rebuild

rebuild the crash kernel initramfs.

propagate

Helps to setup key authentication for ssh storage since it's impossible to use password authentication during kdump.

showmem

Prints the size of reserved memory for the crash kernel in megabytes.

estimate

Estimate a suitable crashkernel value for the current machine. This is a best-effort estimate. It will print a recommended crashkernel value based on the current kdump setup, and list some details of memory usage.

get-default-crashkernel

Return the default crashkernel value provided by kexec-tools.

reset-crashkernel [--kernel=path_to_kernel] [--reboot]

Reset crashkernel to default value recommended by kexec-tools. If no kernel is specified, will reset KDUMP_KERNELVER if it's defined in /etc/sysconfig/kdump or the current running kernel's crashkernel value if KDUMP_KERNELVER is empty. You can also specify --kernel=ALL and --kernel=DEFAULT which have the same meaning as grubby's kernel-path=ALL and kernel-path=DEFAULT. ppc64le supports FADump and supports an additional [--fadump=[on|off|nocma]] parameter to toggle FADump on/off.

If the optional parameter [--reboot] is provided the system will automatically reboot for changes to take effect. If no changes were made to the kernel command line the reboot is omitted.

Note: The memory requirements for kdump varies heavily depending on the used hardware and system configuration. Thus the recommended crashkernel might not work for your specific setup. Please test if kdump works after resetting the crashkernel value.

test [--force]

Test the kdump by actually trigger the system crash & dump, and check if a vmcore can really be generated successfully based on current config and environment. After system reboot back to normal, check the test result by "kdumpctl status".

If the optional parameter [--force] is provided, there will be no interact before triggering the system crash. Dangerous though, this option is meant for automation testing.

kdump.conf(5), mkdumprd(8)

kdump.conf(5), kdumpctl_selinux(8).